1. Field of the Invention
This invention relates to a sheet materials conveying apparatus having a curving conveyance route placed among conveying means and to, for example, a sheet material conveying apparatus used for recording apparatuses such as printers, photocopiers, and facsimile machines.
2. Description of Related Art
Conventionally, a serial recording apparatus, as a recording apparatus of this type, has been known in which making recording on a surface of a recording medium in moving a carriage mounting a recording head in a width direction perpendicular to the recording medium conveyance direction. With this serial recording apparatus, images are recorded on the recording media in repeating alternatively conveyance of the recording media and recording with the carriage doing scanning.
Known also is a line recording apparatus in which a recording head having a substantially recording medium width is mounted to convey the recording media and to record images on the recording media in the width direction.
On the other hand, increasing number is an apparatus having the following structure that can be used commonly for both types. The apparatus automatically feeds, by a feeding means, recording media held at a recording medium holding member such as tray, cassette, or the like, and conveys the recording media to a conveying means via a curving conveyance route.
For example, as shown in FIG. 11, a recording medium fed in a right direction in FIG. 11 from a tray 100 serving as a recording paper holding member by means of a feeding roller 101 as a feeding means is fed to a paper feeding roller 102 as a conveying means in a left direction in FIG. 11 via a conveyance route curving in a U-turn shape. Placing such a curving conveyance route can render the recording apparatus compact and the recording medium or paper easily handled by the users.
Recently, high quality images are demanded, and while high resolution printing can be realized by the above recording head, such recording apparatuses seek to raise conveyance accuracy of the recording material.
In a case that the recording apparatus is made thus compact and that the conveyance route from the feeding roller 101 serving as the feeding means to the paper feeding roller 102 serving as the conveying means is made of a conveyance route curving in the U-turn shape, such a recording apparatus may poses the following problems.
For example, as shown in FIG. 11, where the conveyance route curving in the U-turn shape is formed of a guide-rail-shaped stable member 105, the recording medium may be first subject to lower conveyance accuracy when the feeding roller 102 conveys the recording medium. This is because when the feeding roller 102 receives the recording medium, the rear end of the recording medium is still located at the curving conveyance route, and consequently, a rear side load occurs. Particularly, when the recording medium or the like having a thick thickness is conveyed, the rigidity of the recording medium increases the load, thereby rendering the conveyance accuracy apparently impaired.
Second, when the recording medium is sent to the conveyance roller 102 by the feeding roller 101, large resistance force occurs because the front end of the recording medium passes through the curving conveyance route. Similarly to the first problem, particularly when the recording medium or the like having a thick thickness is conveyed, the rigidity of the recording medium produces larger resistance force, and this resistance force may induce slip of the feeding roller 101. To avoid this, the feeding roller 101 has to receive feeding force overcoming the above resistance force, and therefore, the torque of the drive source and the strength of the feeding roller 101 have to be increased, so that such an apparatus may invite higher production costs.
To solve the above problems (namely, first, rear side load for the paper feeding roller 102 as a conveyance means, second, front side resistance for the feeding roller 101 as a feeding means), a structure shown in FIG. 12 has been proposed. A feeding roller 103 is provided at the curving conveyance route portion, in comparison with FIG. 11, and pressing rollers 104 are provided as pressing members for pressing the recording medium against the feeding roller 103.
This structure, the recording medium held in the recording holding member such as a tray or cassette is fed to the feeding roller 103 by the feeding roller 101. The recording medium clamped with the feeding roller 103 and the pressing roller 104 is sent to the conveying roller 102 according to the rotation of the feeding roller 103. While the recording medium is conveyed by the conveying roller 102, the feeding roller 103 rotates at the same time in association with the above conveyance.
According to this structure, the above problems (first, rear side load for the paper feeding roller 102 as a conveyance means, second, front side resistance for the feeding roller 101 as a feeding means) can be solved, but the following new problems may be posed by the conveyance function of the feeding roller 103 and the pressing roller 104. If the conveyance amount of the feeding roller 103 is small with respect to the paper feeding roller 102, rear side load may remain, and conversely, if the conveyance amount of the feeding roller 103 is large, force on a pushing side may work, even though the rear side load becomes subtle, so rendering worse the conveyance accuracy in the same way as of the rear side load. Moreover, vibrations made when the rear end of the recording medium comes out of the nip portion between the feeding roller 103 and the pressing roller 104 may render worse the conveyance accuracy.
The apparatus has a structure that the pressing roller 104 is pressed onto the feeding roller 103, so that a load is exerted to the feeding roller 103, and that extra drive force is required for this structure. Therefore, the torque of the drive source that provides drive force to the feeding roller 103 is necessarily increased, and consequently, the apparatus may increase the product costs.
This invention is conceived to solve the above problems on the conventional arts. It is an object of the invention to provide an apparatus preventing the conveyance accuracy from becoming worse during recording medium conveyance by the conveying means according to formation of the curving conveyance route between the feeding means and the conveying means and also preventing the product costs for larger drive force from becoming higher.
A representative structure according to this invention to accomplish the above object is including first conveying means for conveying a sheet material; second conveying means for conveying, on a downstream side in a sheet material conveyance direction of the first conveying means, the sheet material; and a plurality of guide members for forming a curving conveyance route located between the first conveying means and the second conveying means, wherein the guide member forming the curving conveyance route located on an inner side among the guide members is a rotary body rotatably, which is arranged with no pressing member for pressing the sheet material to the rotary body.
According to the above structure, among the guide members forming the curving conveyance route between the first conveying means and the second conveying means, the guide member located on an inner side is formed of a rotatable rotary body, and the structure has no pressing member for pressing the sheet material to the rotary body, so that the apparatus can prevent the conveyance accuracy from becoming worse during recording medium conveyance by the conveying means and also prevent the product costs for increasing conveyance power of the conveying means from becoming higher.